RE: [Xen-devel] [PATCH] Fix softlockup issue after vcpu hotplug

["Graham, Simon" <Simon.Graham@xxxxxxxxxxx>]

> On 30/1/07 09:54, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
> 
> > Another simple approach to trigger such warning is to let
> > __xen_suspend() jumps to smp_resume immediately after
> > smp_suspend, as a test case for suspend cancel. People can
> > observe all vcpus except vcpu0 fall into that warning frequently.
> 
> Do you know if this problem has been observed across many versions of
> Xen or
> e.g., only after the upgrade to 2.6.18?
> 

I'm not sure but I think that we've been seeing something very similar
when live migrating domains with 3.0.3/2.6.16.29) -- my understanding is
that the live migration code takes the domain down to UP, does the
migration and then restores SMP -- we VERY often see soft lockup
messages following this (several times per night in our regression
testing) with stack traces identical to those posted by Kevin.

I also added some instrumentation and in every single case, the 'stolen'
time is > 5s when we see the soft lockup.

Simon


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